Double Bottom Hydro Cylnders

Hi There
Does anyone have a survey list of all hydro jack mfg. that have data on the hydro cylnders, everyones concerned about removing single bottom cylnders. It seems like someone has allready made a list of equipment to be concerned about.

Answers

Anything Pre-1970 has been considered by ANSI to be single bottom,
although there jacks out there of this vintage that aren't... The
Code requirements for anything Pre-1970 are Relief Valve and Pressure
Tests every 6 months...

It is my opinion that a lot of the single / double bottom jack stuff
is a ripoff. We replaced a number of jacks that were purported to be
single bottom by the OEM, and they turned out to be double bottom.
These jacks did not have one single pit in the cylinder.

Additionally, Esco had exclusively used double bottome jacks since
1960. Yes the code changed in 1970, and some big OEMs didnt keep good
records, or choose to discard the records and push for jack
replacements using the "safety issue" as the clencher.

The problem is that you cant advise an owner aganst replacement,
unless you can prove that there's a double bottom down there.